The Diagnostic Core will provide a framework for the identification and neurobehavioral screening evaluation of subjects entering into the individual projects. Before the state-of-the-art experimental procedures outlined in the Projects can be applied to the study populations, it is crucial to determine whether individual children meet the inclusionary and exclusionary criteria for the group to which they are assigned. In addition, the Core neurological data and screening battery provide a framework in which to better understand athe significance of the experimental data provided in the subprojects. The major responsibilities of the Diagnostic Core are; 1. Identification and induction of experimental and control subjects. 2. Screening of subjects for selection criteria as defined for each research project. 3. Administration and analysis of medical and developmental questionnaires and medical/neurologic examinations. 4. Administration and scoring of a battery of standardized tests to all experimental subjects, and to a subset of controls. 5. Tracking of all subjects form entry to completion of testing. 6. Provision of MRI scans with clinical interpretations and morphometric analysis. 7. Collaboration with Project Investigators to relate these diagnostic findings tot he experimental findings obtained in the Project studies.